/* ============================================================
   Ôn Thi Y Khoa — Gold × Navy Glassmorphism
   ============================================================ */

:root {
  /* Lesson accent (overridden per data-lesson on #app) */
  --c-lesson: var(--c-gold);
  --c-lesson-dim: rgba(230,168,23,.13);
  --c-lesson-border: rgba(230,168,23,.38);

  /* Gold palette */
  --c-gold: #e6a817;
  --c-gold-bright: #f5c030;
  --c-gold-text: #fcd34d;
  --c-gold-dim: rgba(230,168,23,.15);
  --c-gold-glow: rgba(245,192,48,.25);

  /* Navy/dark background */
  --c-bg: #080c14;
  --c-surface: rgba(16,22,40,.92);
  --c-surface-solid: #101628;
  --c-border: rgba(230,168,23,.12);
  --c-border-strong: rgba(230,168,23,.28);

  /* Semantic */
  --c-primary: var(--c-gold);
  --c-primary-hover: var(--c-gold-bright);
  --c-primary-light: rgba(230,168,23,.1);
  --c-success: #34d399;
  --c-success-light: rgba(52,211,153,.08);
  --c-danger: #f87171;
  --c-danger-light: rgba(248,113,113,.08);
  --c-warn: #f5c030;
  --c-warn-light: rgba(245,192,48,.08);

  /* Lesson accent colors */
  --c-bai24: #a78bfa;
  --c-bai25: #22d3ee;
  --c-bai26: #34d399;

  /* Text */
  --c-text: #f0f4ff;
  --c-text-2: #94a3b8;
  --c-text-3: #4a5578;

  /* Spacing */
  --sp-xs: .25rem;
  --sp-sm: .5rem;
  --sp-md: 1rem;
  --sp-lg: 1.5rem;
  --sp-xl: 2rem;

  /* Radius */
  --r-sm: 6px;
  --r-md: 12px;
  --r-lg: 18px;
  --r-full: 9999px;

  /* Glass */
  --glass-bg: rgba(16,22,40,.88);
  --glass-blur: blur(20px) saturate(160%);
  --glass-border: 1px solid rgba(230,168,23,.13);

  /* Shadow */
  --sh-sm: 0 2px 8px rgba(0,0,0,.4);
  --sh-md: 0 4px 20px rgba(0,0,0,.5), 0 0 0 1px rgba(230,168,23,.06);
  --sh-gold: 0 0 28px rgba(230,168,23,.28), 0 4px 12px rgba(0,0,0,.4);

  /* Nav heights */
  --nav-top: 56px;
  --nav-bottom: 64px;
}

/* ── Reset ── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { font-size: 16px; -webkit-text-size-adjust: 100%; }

body {
  font-family: -apple-system, 'SF Pro Text', 'Segoe UI', system-ui, sans-serif;
  background: var(--c-bg);
  color: var(--c-text);
  line-height: 1.6;
  min-height: 100dvh;
  -webkit-font-smoothing: antialiased;
  background-image:
    radial-gradient(ellipse 80% 50% at 50% -10%, rgba(230,168,23,.07) 0%, transparent 55%),
    radial-gradient(ellipse 40% 30% at 85% 85%, rgba(99,102,241,.05) 0%, transparent 50%);
}

/* ── Top navigation ── */
.top-nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: var(--nav-top);
  border-bottom: 1px solid rgba(230,168,23,.1);
  display: flex;
  align-items: center;
  padding: 0 var(--sp-md);
  gap: var(--sp-sm);
  z-index: 200;
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  background: rgba(8,12,20,.92);
}

.nav-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  padding: 0;
  border: 1px solid rgba(255,255,255,.15);
  border-radius: var(--r-md);
  background: transparent;
  color: var(--c-text-2);
  cursor: pointer;
  transition: background .15s, border-color .15s, color .15s;
  flex-shrink: 0;
}
.nav-btn:hover { background: rgba(255,255,255,.07); border-color: rgba(255,255,255,.3); color: var(--c-text); }
.nav-btn:active { opacity: .8; }
.nav-btn[hidden] { display: none; }
.nav-btn:disabled { opacity: .3; cursor: default; pointer-events: none; }
.nav-btn-exit { color: var(--c-danger); border-color: rgba(248,113,113,.3); }
.nav-btn-exit:hover { color: var(--c-danger); background: rgba(248,113,113,.08); border-color: rgba(248,113,113,.6); }
.nav-btn-exit svg { transform: scaleX(-1); }

.nav-quiz-cluster {
  position: absolute;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  align-items: center;
  gap: 6px;
}

.nav-next-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  padding: 0;
  border: none;
  border-radius: var(--r-md);
  background: linear-gradient(135deg, var(--c-gold-bright), var(--c-gold));
  color: #1a1000;
  cursor: pointer;
  flex-shrink: 0;
  transition: opacity .15s;
}
.nav-next-btn:hover  { opacity: .88; }
.nav-next-btn:active { opacity: .72; }
/* keeps btn-nav-next in flow so cluster width is stable; invisible but not collapsed */
.nav-next-btn[hidden] { display: inline-flex !important; visibility: hidden; pointer-events: none; }

.font-size-ctrl {
  display: flex;
  align-items: center;
  height: 30px;
  border: 1px solid rgba(255,255,255,.14);
  border-radius: var(--r-sm);
  overflow: hidden;
  flex-shrink: 0;
}
.font-size-ctrl[hidden] { display: none; }
.fsc-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  height: 100%;
  padding: 0 8px;
  background: transparent;
  border: none;
  color: var(--c-text-2);
  cursor: pointer;
  font-weight: 700;
  transition: background .15s, color .15s;
  line-height: 1;
}
.fsc-dec { font-size: .72rem; }
.fsc-inc { font-size: 1rem; }
.fsc-btn:hover  { background: rgba(255,255,255,.08); color: var(--c-text); }
.fsc-btn:active { background: rgba(255,255,255,.14); }
.fsc-btn.active { color: var(--c-text); }
.fsc-div {
  width: 1px;
  height: 60%;
  background: rgba(255,255,255,.16);
  flex-shrink: 0;
}
.fsc-div[hidden] { display: none; }
.nav-counter {
  font-size: .75rem;
  font-weight: 700;
  color: var(--c-text-2);
  padding: 0 .5rem;
  white-space: nowrap;
  line-height: 1;
}
.nav-counter[hidden] { display: none; }

.nav-title {
  flex: 1;
  font-size: .88rem;
  font-weight: 700;
  color: var(--c-text);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  text-align: center;
  letter-spacing: .01em;
}

/* ── Bottom tab bar (mobile) ── */
.bottom-tabs {
  position: fixed;
  bottom: 0; left: 0; right: 0;
  height: var(--nav-bottom);
  border-top: 1px solid rgba(230,168,23,.1);
  display: flex;
  align-items: stretch;
  z-index: 200;
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  background: rgba(8,12,20,.94);
}

.tab-btn {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 3px;
  border: none;
  background: transparent;
  color: var(--c-text-3);
  cursor: pointer;
  transition: color .15s;
  padding: var(--sp-xs) 0;
  position: relative;
}
.tab-label {
  font-size: .6rem;
  font-weight: 600;
  letter-spacing: .03em;
  line-height: 1;
}
.tab-btn.active { color: var(--c-gold-text); }
.tab-btn.active::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 28%; right: 28%;
  height: 2px;
  background: linear-gradient(90deg, var(--c-gold-bright), var(--c-gold));
  border-radius: var(--r-full) var(--r-full) 0 0;
}
.tab-btn:active { opacity: .7; }

/* Desktop nav links */
.desktop-nav-links { display: none; }

/* ── Page layout ── */
#app {
  padding-top: calc(var(--nav-top) + var(--sp-md));
  padding-bottom: calc(var(--nav-bottom) + var(--sp-md));
  padding-left: var(--sp-md);
  padding-right: var(--sp-md);
  max-width: 720px;
  margin: 0 auto;
  min-height: 100dvh;
}

/* ── Glass card ── */
.card {
  background: var(--glass-bg);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border-radius: var(--r-lg);
  box-shadow: var(--sh-md);
  border: var(--glass-border);
  overflow: hidden;
}
.card-body { padding: var(--sp-lg); }
.card-header {
  padding: var(--sp-md) var(--sp-lg);
  border-bottom: 1px solid var(--c-border);
  font-weight: 600;
  font-size: .875rem;
  color: var(--c-text-2);
  text-transform: uppercase;
  letter-spacing: .06em;
}

/* ── Buttons ── */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--sp-sm);
  padding: .625rem 1.25rem;
  border: none;
  border-radius: var(--r-md);
  font-size: .9rem;
  font-weight: 700;
  cursor: pointer;
  transition: opacity .15s, transform .1s, box-shadow .15s;
  line-height: 1.4;
  white-space: nowrap;
}
.btn:active { transform: scale(.97); }
.btn:disabled { opacity: .35; cursor: not-allowed; transform: none; }

.btn-primary {
  background: linear-gradient(135deg, var(--c-gold-bright) 0%, var(--c-gold) 100%);
  color: #0a0700;
  box-shadow: 0 2px 12px rgba(230,168,23,.3);
}
.btn-primary:hover:not(:disabled) {
  opacity: .92;
  box-shadow: 0 4px 20px rgba(230,168,23,.45);
}

.btn-ghost {
  background: transparent;
  color: var(--c-gold-text);
  border: 1.5px solid rgba(230,168,23,.32);
}
.btn-ghost:hover:not(:disabled) {
  background: var(--c-primary-light);
  border-color: var(--c-gold);
}

.btn-surface {
  background: rgba(255,255,255,.05);
  color: var(--c-text);
  border: 1.5px solid rgba(255,255,255,.1);
}
.btn-surface:hover:not(:disabled) { background: rgba(255,255,255,.09); }

.btn-full { width: 100%; }
.btn-lg { padding: .85rem 1.5rem; font-size: 1rem; }

/* ── HOME SCREEN ── */
.home-hero { padding: var(--sp-lg) 0 var(--sp-md); }

.home-hero-title {
  font-size: 1.75rem;
  font-weight: 900;
  background: linear-gradient(135deg, var(--c-gold-bright) 0%, var(--c-gold) 55%, #c8870e 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  letter-spacing: -.03em;
  line-height: 1.2;
  margin-bottom: var(--sp-xs);
}
.home-hero-sub { color: var(--c-text-2); font-size: .9rem; }

/* Lesson cards */
.lesson-list { display: flex; flex-direction: column; gap: var(--sp-md); margin-top: var(--sp-md); }

.lesson-card {
  background: var(--glass-bg);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border-radius: var(--r-lg);
  box-shadow: var(--sh-sm);
  border: var(--glass-border);
  padding: var(--sp-lg);
  cursor: pointer;
  transition: box-shadow .2s, border-color .2s, transform .15s;
  display: flex;
  align-items: center;
  gap: var(--sp-md);
}
.lesson-card:hover {
  box-shadow: var(--sh-gold);
  border-color: rgba(230,168,23,.35);
  transform: translateY(-2px);
}
.lesson-card:active { transform: scale(.98); }

.lesson-icon {
  width: 52px;
  height: 52px;
  border-radius: var(--r-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: .75rem;
  font-weight: 800;
  letter-spacing: .04em;
  flex-shrink: 0;
}
.lesson-icon.bai24 { background: linear-gradient(135deg, #2d1f4e, #1e1535); color: #c4b5fd; border: 1px solid rgba(167,139,250,.2); }
.lesson-icon.bai25 { background: linear-gradient(135deg, #0c2a35, #071e28); color: #67e8f9; border: 1px solid rgba(34,211,238,.2); }
.lesson-icon.bai26 { background: linear-gradient(135deg, #052e16, #03200f); color: #6ee7b7; border: 1px solid rgba(52,211,153,.2); }

.lesson-info { flex: 1; min-width: 0; }
.lesson-name { font-weight: 700; font-size: 1rem; margin-bottom: 2px; color: var(--c-text); }
.lesson-meta { font-size: .8rem; color: var(--c-text-2); }

.lesson-badge {
  font-size: .75rem;
  font-weight: 700;
  padding: 4px 10px;
  border-radius: var(--r-full);
  background: rgba(255,255,255,.06);
  color: var(--c-text-2);
  border: 1px solid rgba(255,255,255,.1);
  flex-shrink: 0;
}

/* Stats row */
.stats-row {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--sp-sm);
  margin: var(--sp-md) 0;
}
.stat-tile {
  background: var(--glass-bg);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border-radius: var(--r-md);
  padding: var(--sp-md);
  border: var(--glass-border);
  text-align: center;
}
.stat-tile .val { font-size: 1.4rem; font-weight: 900; color: var(--c-text); }
.stat-tile .lbl { font-size: .7rem; color: var(--c-text-3); margin-top: 2px; }

/* ── LESSON DETAIL ── */
.lesson-header-band {
  margin: 0 calc(-1 * var(--sp-md));
  padding: var(--sp-lg) var(--sp-lg);
  margin-top: calc(-1 * var(--sp-md));
  position: relative;
  overflow: hidden;
}
.lesson-header-band::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, rgba(230,168,23,.08) 0%, transparent 60%);
  pointer-events: none;
}
.lesson-header-band.bai24 { background: linear-gradient(135deg, #1a1040, #0d0b20); border-bottom: 1px solid rgba(167,139,250,.12); }
.lesson-header-band.bai25 { background: linear-gradient(135deg, #071e28, #040f16); border-bottom: 1px solid rgba(34,211,238,.12); }
.lesson-header-band.bai26 { background: linear-gradient(135deg, #03200f, #011509); border-bottom: 1px solid rgba(52,211,153,.12); }

/* Lesson accent CSS variables — set via data-lesson on #app */
#app[data-lesson="bai24"] { --c-lesson: var(--c-bai24); --c-lesson-dim: rgba(167,139,250,.14); --c-lesson-border: rgba(167,139,250,.42); }
#app[data-lesson="bai25"] { --c-lesson: var(--c-bai25); --c-lesson-dim: rgba(34,211,238,.12);  --c-lesson-border: rgba(34,211,238,.40); }
#app[data-lesson="bai26"] { --c-lesson: var(--c-bai26); --c-lesson-dim: rgba(52,211,153,.12);  --c-lesson-border: rgba(52,211,153,.40); }

.lesson-page-title { font-size: 1.2rem; font-weight: 800; color: var(--c-text); margin-bottom: 4px; position: relative; }
.lesson-page-sub { font-size: .85rem; color: var(--c-text-2); position: relative; }

.section-label {
  font-size: .68rem;
  font-weight: 700;
  color: var(--c-text-3);
  text-transform: uppercase;
  letter-spacing: .12em;
  margin: var(--sp-lg) 0 var(--sp-sm);
}

/* Topic chips */
.chip-group { display: flex; flex-wrap: wrap; gap: var(--sp-sm); }
.chip {
  padding: .45rem .9rem;
  border-radius: var(--r-full);
  font-size: .85rem;
  font-weight: 500;
  border: 1.5px solid rgba(255,255,255,.1);
  background: rgba(255,255,255,.04);
  color: var(--c-text-2);
  cursor: pointer;
  transition: all .15s;
}
.chip.active {
  background: var(--c-lesson-dim);
  border-color: var(--c-lesson-border);
  color: var(--c-lesson);
  font-weight: 700;
  box-shadow: none;
}
.chip:active { transform: scale(.95); }

/* Count selector */
.count-group { display: flex; gap: var(--sp-sm); }
.count-chip {
  width: 52px;
  height: 40px;
  border-radius: var(--r-md);
  font-size: .9rem;
  font-weight: 700;
  border: 1.5px solid rgba(255,255,255,.1);
  background: rgba(255,255,255,.04);
  color: var(--c-text-2);
  cursor: pointer;
  transition: all .15s;
  display: flex;
  align-items: center;
  justify-content: center;
}
.count-chip.active {
  background: var(--c-lesson-dim);
  border-color: var(--c-lesson-border);
  color: var(--c-lesson);
  box-shadow: none;
}

/* Type filter */
.type-grid { display: grid; grid-template-columns: 1fr 1fr; gap: var(--sp-sm); }
.type-tile {
  padding: var(--sp-sm) var(--sp-md);
  border-radius: var(--r-md);
  border: 1.5px solid rgba(255,255,255,.08);
  background: rgba(255,255,255,.03);
  cursor: pointer;
  transition: all .15s;
  text-align: left;
}
.type-tile.active {
  border-color: var(--c-lesson-border);
  background: var(--c-lesson-dim);
}
.type-tile.active .type-code { color: var(--c-lesson); }
.type-tile.active .type-name { color: var(--c-text); }
.type-tile .type-code { font-size: .68rem; font-weight: 700; color: var(--c-text-3); text-transform: uppercase; letter-spacing: .04em; }
.type-tile .type-name { font-size: .85rem; font-weight: 600; color: var(--c-text); margin-top: 2px; }

/* ── QUIZ SCREEN ── */
.quiz-progress {
  display: flex;
  flex-direction: column;
  gap: 6px;
  margin-bottom: var(--sp-md);
}
.quiz-counter-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.btn-sm { padding: .38rem .8rem; font-size: .82rem; }
.progress-track {
  height: 4px;
  background: rgba(255,255,255,.07);
  border-radius: var(--r-full);
  overflow: hidden;
}
.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--c-gold-bright), var(--c-gold));
  border-radius: var(--r-full);
  transition: width .35s ease;
}
.progress-label { font-size: .8rem; font-weight: 600; color: var(--c-text-2); white-space: nowrap; }

.question-card {
  background: var(--glass-bg);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border-radius: var(--r-lg);
  box-shadow: var(--sh-md);
  border: var(--glass-border);
  padding: var(--sp-lg);
  margin-bottom: var(--sp-md);
}

.question-meta {
  display: flex;
  align-items: center;
  gap: var(--sp-sm);
  margin-bottom: var(--sp-md);
}
.q-type-badge {
  font-size: .62rem;
  font-weight: 700;
  padding: 3px 8px;
  border-radius: var(--r-full);
  text-transform: uppercase;
  letter-spacing: .05em;
}
.q-type-badge.L1_recall        { background: rgba(251,191,36,.1);  color: #fcd34d; border: 1px solid rgba(251,191,36,.18); }
.q-type-badge.L2_comprehension  { background: rgba(96,165,250,.1);  color: #93c5fd; border: 1px solid rgba(96,165,250,.18); }
.q-type-badge.L3_application    { background: rgba(52,211,153,.1);  color: #6ee7b7; border: 1px solid rgba(52,211,153,.18); }
.q-type-badge.L4_analysis       { background: rgba(167,139,250,.1); color: #c4b5fd; border: 1px solid rgba(167,139,250,.18); }
.q-type-badge.L5_reasoning      { background: rgba(248,113,113,.1); color: #fca5a5; border: 1px solid rgba(248,113,113,.18); }
.q-type-badge.L6_synthesis      { background: rgba(244,114,182,.1); color: #f9a8d4; border: 1px solid rgba(244,114,182,.18); }

.q-num { font-size: .8rem; color: var(--c-text-3); margin-left: auto; }

.question-stem {
  font-size: 1rem;
  font-weight: 500;
  line-height: 1.7;
  color: var(--c-text);
}

/* Options */
.options-list { display: flex; flex-direction: column; gap: var(--sp-sm); margin-top: var(--sp-lg); }

.option-btn {
  width: 100%;
  text-align: left;
  padding: var(--sp-md);
  border-radius: var(--r-md);
  border: 1.5px solid rgba(255,255,255,.08);
  background: rgba(255,255,255,.03);
  cursor: pointer;
  font-size: .925rem;
  line-height: 1.5;
  color: var(--c-text);
  transition: border-color .15s, background .15s;
  display: flex;
  gap: var(--sp-sm);
  align-items: flex-start;
}
.option-key {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: rgba(255,255,255,.06);
  border: 1.5px solid rgba(255,255,255,.12);
  font-size: .8rem;
  font-weight: 700;
  flex-shrink: 0;
  transition: background .15s, border-color .15s, color .15s;
  color: var(--c-text-2);
}
.option-text { padding-top: 3px; flex: 1; }

.option-btn:hover:not(:disabled) {
  border-color: rgba(230,168,23,.38);
  background: var(--c-primary-light);
}
.option-btn:hover:not(:disabled) .option-key {
  background: linear-gradient(135deg, var(--c-gold-bright), var(--c-gold));
  border-color: transparent;
  color: #0a0700;
}
.option-btn:disabled { cursor: default; }

.option-btn.correct {
  border-color: rgba(52,211,153,.38);
  background: var(--c-success-light);
}
.option-btn.correct .option-key {
  background: var(--c-success);
  border-color: transparent;
  color: #052e16;
}
.option-btn.wrong {
  border-color: rgba(248,113,113,.38);
  background: var(--c-danger-light);
}
.option-btn.wrong .option-key {
  background: var(--c-danger);
  border-color: transparent;
  color: #3b0a0a;
}

/* Explanation box */
.explanation-box {
  margin-top: var(--sp-md);
  padding: var(--sp-md) var(--sp-lg);
  background: rgba(245,192,48,.06);
  border-left: 3px solid var(--c-gold);
  border-radius: 0 var(--r-md) var(--r-md) 0;
}
.explanation-label {
  font-size: .68rem;
  font-weight: 700;
  color: var(--c-gold);
  text-transform: uppercase;
  letter-spacing: .1em;
  margin-bottom: var(--sp-sm);
}
.explanation-verdict { font-size: .9rem; font-weight: 700; color: var(--c-text); margin-bottom: var(--sp-sm); }
.explanation-text { font-size: .9rem; color: var(--c-text-2); line-height: 1.65; }

/* Note box (per question) */
.note-box {
  margin-top: var(--sp-sm);
  padding: var(--sp-sm) var(--sp-md) var(--sp-md);
  background: rgba(255,255,255,.02);
  border: 1px solid rgba(255,255,255,.07);
  border-radius: var(--r-md);
}
.note-label {
  font-size: .65rem;
  font-weight: 700;
  color: var(--c-text-3);
  text-transform: uppercase;
  letter-spacing: .1em;
  margin-bottom: var(--sp-sm);
}
.note-textarea {
  width: 100%;
  background: rgba(255,255,255,.04);
  border: 1px solid rgba(255,255,255,.1);
  border-radius: var(--r-sm);
  color: var(--c-text);
  font-size: .875rem;
  font-family: inherit;
  line-height: 1.5;
  padding: var(--sp-sm);
  resize: vertical;
  min-height: 60px;
  outline: none;
  transition: border-color .15s;
}
.note-textarea::placeholder { color: var(--c-text-3); }
.note-textarea:focus { border-color: rgba(230,168,23,.35); }

/* Quiz footer */
.quiz-footer {
  display: flex;
  justify-content: flex-end;
  gap: var(--sp-sm);
  padding: var(--sp-sm) 0;
}

/* ── RESULTS ── */
.results-hero {
  text-align: center;
  padding: var(--sp-xl) 0 var(--sp-lg);
}

.score-ring {
  width: 120px;
  height: 120px;
  border-radius: 50%;
  border: 5px solid var(--c-gold);
  box-shadow: var(--sh-gold);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  margin: 0 auto var(--sp-md);
  background: radial-gradient(circle at center, rgba(230,168,23,.07) 0%, transparent 70%);
}
.score-ring.excellent {
  border-color: var(--c-success);
  box-shadow: 0 0 32px rgba(52,211,153,.3), 0 0 60px rgba(52,211,153,.1);
}
.score-ring.poor {
  border-color: var(--c-danger);
  box-shadow: 0 0 24px rgba(248,113,113,.25);
}

.score-big {
  font-size: 2.4rem;
  font-weight: 900;
  background: linear-gradient(135deg, var(--c-gold-bright), var(--c-gold));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  line-height: 1;
}
.score-ring.excellent .score-big {
  background: linear-gradient(135deg, #6ee7b7, #34d399);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.score-ring.poor .score-big {
  background: linear-gradient(135deg, #fca5a5, #f87171);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.score-denom { font-size: .8rem; color: var(--c-text-3); }
.results-grade { font-size: 1.4rem; font-weight: 800; color: var(--c-text); margin-bottom: 4px; }
.results-pct { font-size: 1rem; color: var(--c-text-2); }

.results-actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-sm);
  justify-content: center;
  margin-top: var(--sp-lg);
}

/* Review items */
.review-section { margin-top: var(--sp-xl); }
.review-section-title { font-size: 1rem; font-weight: 700; color: var(--c-text); margin-bottom: var(--sp-md); }

.review-item {
  background: var(--glass-bg);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border-radius: var(--r-md);
  padding: var(--sp-md) var(--sp-lg);
  margin-bottom: var(--sp-sm);
  border: 1px solid rgba(52,211,153,.12);
  border-left: 4px solid var(--c-success);
}
.review-item.wrong {
  border-left-color: var(--c-danger);
  border-color: rgba(248,113,113,.12);
}
.review-item-stem { font-size: .9rem; font-weight: 600; margin-bottom: var(--sp-sm); color: var(--c-text); }
.review-item-answers { font-size: .85rem; display: flex; flex-direction: column; gap: 4px; }
.review-correct { color: var(--c-success); font-weight: 600; }
.review-wrong { color: var(--c-danger); }
.review-expl {
  margin-top: var(--sp-sm);
  padding: var(--sp-sm) var(--sp-md);
  background: rgba(245,192,48,.05);
  border-radius: var(--r-sm);
  font-size: .82rem;
  color: var(--c-text-2);
  line-height: 1.6;
}
.review-note {
  margin-top: var(--sp-sm);
  padding: var(--sp-sm) var(--sp-md);
  background: rgba(148,163,184,.04);
  border-radius: var(--r-sm);
  border-left: 2px solid rgba(148,163,184,.18);
}
.review-note-label { font-size: .65rem; font-weight: 700; color: var(--c-text-3); text-transform: uppercase; letter-spacing: .08em; margin-bottom: 2px; }
.review-note-text { font-size: .82rem; color: var(--c-text-3); line-height: 1.5; font-style: italic; }

/* ── HISTORY SCREEN ── */
.history-list { display: flex; flex-direction: column; gap: var(--sp-md); }

.history-session {
  background: var(--glass-bg);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border-radius: var(--r-lg);
  border: var(--glass-border);
  overflow: hidden;
  box-shadow: var(--sh-sm);
}
.history-session-header {
  display: flex;
  align-items: center;
  gap: var(--sp-md);
  padding: var(--sp-md) var(--sp-lg);
  cursor: pointer;
  transition: background .15s;
  border: none;
  background: transparent;
  width: 100%;
  text-align: left;
}
.history-session-header:hover { background: rgba(255,255,255,.03); }

.history-session-score {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  border: 3px solid var(--c-gold);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: .82rem;
  font-weight: 900;
  color: var(--c-gold-text);
  flex-shrink: 0;
}
.history-session-score.excellent { border-color: var(--c-success); color: var(--c-success); }
.history-session-score.poor { border-color: var(--c-danger); color: var(--c-danger); }

.history-session-info { flex: 1; min-width: 0; }
.history-session-title { font-size: .9rem; font-weight: 700; color: var(--c-text); }
.history-session-meta { font-size: .75rem; color: var(--c-text-2); margin-top: 2px; }

.history-chevron { color: var(--c-text-3); font-size: .75rem; transition: transform .2s; flex-shrink: 0; }
.history-chevron.open { transform: rotate(180deg); }

.history-session-body {
  padding: 0 var(--sp-lg) var(--sp-md);
  border-top: 1px solid var(--c-border);
  display: none;
}
.history-session-body.open { display: block; }

.history-q-row {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 4px var(--sp-sm);
  padding: var(--sp-sm) 0;
  border-bottom: 1px solid rgba(255,255,255,.04);
  font-size: .83rem;
}
.history-q-row:last-child { border-bottom: none; }
.history-q-num { color: var(--c-text-3); font-size: .72rem; flex-shrink: 0; min-width: 1.5rem; }
.history-q-stem { flex: 1; min-width: 60%; color: var(--c-text-2); line-height: 1.4; }
.history-q-verdict { flex-shrink: 0; font-weight: 700; font-size: .78rem; }
.history-q-verdict.correct { color: var(--c-success); }
.history-q-verdict.wrong { color: var(--c-danger); }
.history-q-note { flex-basis: 100%; font-size: .77rem; color: var(--c-text-3); padding-left: 1.5rem; font-style: italic; }

/* ── SETTINGS ── */
.settings-list { display: flex; flex-direction: column; gap: var(--sp-sm); }
.settings-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: var(--glass-bg);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border-radius: var(--r-md);
  padding: var(--sp-md) var(--sp-lg);
  border: var(--glass-border);
}
.settings-label { font-size: .9rem; font-weight: 500; color: var(--c-text); }
.settings-value { font-size: .85rem; color: var(--c-text-2); font-weight: 600; }

/* ── Empty / error states ── */
.empty-state {
  text-align: center;
  padding: var(--sp-xl) var(--sp-md);
  color: var(--c-text-2);
}
.empty-state .empty-icon { font-size: 3rem; margin-bottom: var(--sp-md); }
.empty-state p { font-size: .9rem; }

/* ── Desktop ≥768px ── */
@media (min-width: 768px) {
  :root {
    --nav-top: 60px;
    --nav-bottom: 0px;
  }

  #app {
    padding-top: calc(var(--nav-top) + var(--sp-xl));
    padding-bottom: var(--sp-xl);
    padding-left: var(--sp-xl);
    padding-right: var(--sp-xl);
  }

  .bottom-tabs { display: none; }

  .desktop-nav-links {
    display: flex;
    align-items: center;
    gap: 4px;
  }
  .desktop-nav-link {
    font-size: .85rem;
    font-weight: 600;
    color: var(--c-text-2);
    padding: .375rem .875rem;
    border-radius: var(--r-md);
    border: 1px solid transparent;
    background: transparent;
    cursor: pointer;
    transition: all .15s;
    white-space: nowrap;
  }
  .desktop-nav-link:hover {
    background: var(--c-primary-light);
    color: var(--c-gold-text);
    border-color: rgba(230,168,23,.18);
  }
  .desktop-nav-link.active {
    color: var(--c-gold-text);
    font-weight: 700;
    border-color: rgba(230,168,23,.22);
    background: var(--c-primary-light);
  }

  .lesson-list { display: grid; grid-template-columns: 1fr 1fr; gap: var(--sp-md); }
  .stats-row { grid-template-columns: repeat(4, 1fr); }
  .type-grid { grid-template-columns: repeat(3, 1fr); }
  .home-hero-title { font-size: 2.2rem; }
  .font-size-ctrl { display: none; }
}

@media (min-width: 1024px) {
  /* Quiz split view: left = question+options, right = explanation+note */
  .question-card {
    display: flex;
    flex-direction: row;
    gap: var(--sp-xl);
    align-items: flex-start;
  }
  .quiz-left {
    flex: 0 0 56%;
    min-width: 0;
  }
  .quiz-right {
    flex: 1;
    min-width: 0;
    position: sticky;
    top: calc(var(--nav-top) + var(--sp-md));
  }
  .quiz-right .explanation-box { margin-top: 0; }
}

/* ── Font size scaling ── */
html.font-sm .question-stem { font-size: .85rem; }
html.font-sm .option-btn    { font-size: .82rem; }
html.font-sm .explanation-text { font-size: .8rem; }
html.font-sm .history-q-stem  { font-size: .78rem; }

html.font-lg .question-stem { font-size: 1.1rem; }
html.font-lg .option-btn    { font-size: 1rem; }
html.font-lg .explanation-text { font-size: .97rem; }
html.font-lg .history-q-stem  { font-size: .9rem; }

.fsc-btn:disabled { opacity: .3; cursor: default; }


/* ── Safe area ── */
@supports (padding: env(safe-area-inset-bottom)) {
  .bottom-tabs {
    padding-bottom: env(safe-area-inset-bottom);
    height: calc(var(--nav-bottom) + env(safe-area-inset-bottom));
  }
  #app {
    padding-bottom: calc(var(--nav-bottom) + var(--sp-md) + env(safe-area-inset-bottom));
  }
}